i am going to be using seasoned 8inch logs i cut for construction on a small/moderate sized cabin. i'm going to have a woodstove and i know that the moisture levels won't be too bad to have to worry about rot. i don't want to hide any logs used because i'm making this thing from scratch and why hide my hard work and natures beauty. is the woodstove going to be enough to keep my family warm or are there options to ensure an insulated home without ruining the integrity of my logs. does anyone know?

Posted By webo on 19 Apr 2012 01:10 AM
... is the woodstove going to be enough to keep my family warm?

It depends on where you live and how much wood you want to cut.

i live in central new york so i know i'd need a decent amount of firewood. this is my first time building a log cabin, i've built houses from the ground up before but not a cabin. any ideas for backup heat. i sell edenpure heaters i think one of those might be efficeint as a secondary heat source because they're good for 1,000 sq ft and wheel around. i would like to avoid a "permanant" seconday heat source if i can.

Log cabins are not considered "cozy', particularly the DIY variety. You could spend just about everything you think you are saving on varying strategies to insulate and seal the log home in an effort to have efficient heating. The alternative is to waste heat for the next three decades by being a slave to the woodpile or running your backup heater.

BTW, there is nothing "green" about Edenpure heaters. They are straight electric resistance heat.

Not trying to be harsh, but just pointing out that it looks like you are doing the same thing people have done for hundreds of years; building cheap and then wasting energy to heat.

First the construction design, from that a proper heat load and only then the heat source. No wood fired appliance will be convenient lest it be a boiler enhanced by a slab. the only efficient log home is one framed in and insulated. This was the original transition for the pioneers. You may still have wood floors, but find mechanical systems and insulation very easy to install.

because i'm seasoning my own logs i worry about the moisture of insulating right away because i don't want to lock moisture into the logs. would it be benneficial to tough it out for the first few years until the wood has naturally done its thing and then insulate?or is there a method of insulating it at the begining that won't lock in the moisture and rot it out? i agree about the edenpure not being green, i never called it green. and i want to build my shell cheap and with trees and stone from my property, but it will be my permanent residence and i'm not planning on cutting corners and dollars on the inside. my family would hate me for it in these new york winters. all suggestions are and constructive criticism is greatly appreciated.

An 8' log wall will have a lower R value than a 2x4 studwall insulated with R11 batts, sub-code for central NY.

A log wall is impossible to air seal, unless you use some sort of flexible membrane approach that is continuous with the ground vapor barrier, and extends over the ceiling & back down. Seasonal dimensional changes of the wood defeats all other methods of air sealing (even closed cell spray foam.)

There's nothing "efficient" about any resistance-electricity heaters, but in a super-insulated (R40+ on all walls & ceiling) air-tight house with tight U0.20 windows it won't break the bank. If you can get the heat load at design temperature under 24KBTU/hr or less you can heat with a mini-split in most central NY locations for less than half the power use of heating with an EdenPure, and at 15-18cents/kwh there's a strong cost rationale for doing so.

To insulate without seasoning the logs for years, 1x furring on the interior screwed to the logs and installing rigid foam to the furring works. With screened vent holes to the exterior top & bottom at every furring-cavity the drying rates on the interior & exterior sides will be roughly equal, and no moisture can be trapped. The rigid foam can either be trapped in place by a non-strucural interior studwall insulated with batts on which to hang the gypsum, or by another course of furring through-screwed on 24" centers (for minimal thermal bridging) to the other furring, installing the gypsum to the interior furring. The flexible membrane air-barrier can go on either side of the rigid foam, but if you're using fiber-insulated studwall approach putting it between the foam & studwall would be better. (Membrane roofing is probably going to work better long term than housewrap, but it's vapor-impermeable, so placement & mateirals count.) Using reclaimed roofing foam the cost of goods for the insulation can end up comparable to or lower than virgin-stock fiberglass batting in whole-wall R per square foot. (If you need a truckload, The Insulation Depot in Framingham MA will ship- see: http://www.insulationdepot.com/ ). A single 2" layer of polyiso would meet code-min for central NY, but at least doubling that would be worthwhile if you are heating with electricity, or hope to heat with a mini-split.

After several years, so long as you have decent eave & rake overhangs on the roof, you could then install non-expanding injection foam into the vent cavites between the logs and rigid foam if you wanted to grab another R4 or so, but it may or may not be cost effective. as a vented structural cladding you could just leave it, but filling it with foam would lower the likelihood of vermin creating a condo complex in there. From an ant/termite/wasp point of view a "borate only" cellulose fill would be better, since the borates would inhibit wood boring insects from setting up shop in the cavity, and kill those that manage to bore in from the exterior.

wow! thank you! as far as the exterior goes, i plan on chinking the walls. is there anything else i can do to help stop air leaks?

2x4 interior walls, 2" of 2# foam and no worries. Build on a slab and tube it.

Log homes sellers have long discussions as about thermal mass and other factors...

Required---  noted by
 when GeoThermal HVAC'ers got caught
with loops so cold they first said  2200 living over basement sq ft needed 5- 6-Size-rated units... but they were working like 3-tons, avg COP's below 3.0 for a year of data (!)
and then
later found in the early 90's a 3-to-4ton (if using 100% Priority HW , which needs another ton of ground loop) on a TODAY's comparatively 1000-1200 vertical wet borehole footage now called 5  to 6-tons of ground loop (in 52-deg earth), was what was required ,,,

If you're checking + Same results today:
Log homes with HW GT production requirements start at 1-ton ECL, gle loop
then add the home heat load by HVAC'ers or GT'ers who KNOW what peak lows on windy-nights for 2-3 weeks of a winter requires by their installed experience.

T's again IC and D1; and I agree, unless "the leather with no accountable payback is giving the Peace Of Mind... and we live a little longer..."


My shift in punch list is:

get a choice lowest ut'y supplier rate after a first month's bill
after
Better Building and Insulation
Better Distribution (like don't disturb air along walls and ceilings anywhere ...
tiny HVAC, etc. relatively greener...

Posted By BadgerBoilerMN on 19 Apr 2012 08:14 PM
2x4 interior walls, 2" of 2# foam and no worries. Build on a slab and tube it.

2lb foam on log walls usually ends up cracking and leaking as the logs change dimension, warp & shift, and would create uneven drying of the logs leading to checks & cracks unless fully seasoned.  Open cell foam is more flexible and has a better chance of holding up as an air barrier long term.  With 2lb foam applied between the studs of the 2x4 wall it won't perform NEARLY as well as rigid foam between the studs & logs due to the R2 thermal bridging of the studs.

The spray foam solution that might hold air over time would be to set the studwall 1.5-2" from the logs and spraying open cell foam the full depth from logs to gypsum, but that doesn't address the issues of less than fully cured logs.  But it would result in a whole-wall R between R20-R25, counting the R value of the logs + gypsum at R7-R8. (The thermal bridging of the chinking could reduce that to ~R4 if the logs are pretty much full-rounds rather than flattened off substantially.)  By contrast, 2" of rigid iso by itself is R12, and a 2x4 studwall with R13 batts or cellulose + interior gypsum adds another R10 for R22, to which one adds R4-R8 for the logs.  Whether the open cell solution vs the membrane air barrier & rigid foam solution is most cost effective depends on the amount of sweat-equity gets applied, and whether virgin stock vs. reclaimed foam is used.

Building on slab and tubing it makes sense if there's a wood boiler in the future, not so much if relying on propane or oil.  Putting at least R10 of XPS or EPS under the slab makes sense no matter, what, add R5 to that if going for radiant.

Wood stoves & pellet stoves are problematic in log buildings too, since the same seasonal mechanical shifting that makes walls difficult to air seal also creates issues with air-sealing around the venting.  This is another factor leaning heavily toward wood boilers and radiant in this case.

To maintain air tightness at the ceiling, the support for the attic insulation should be the 2x4 studwall, and not the logs, which will  heave & flex seasionally.  The roof itself is best supported by the logs either trussed, or with the tops of the log walls constrained from outward forces of a gabled roof with lightweight joists or turnbuckles.  The wall-foam of the studwall should extend upward to at least the top of the insulation-support joists as a thermal break.

With this approach the structural shell of roof & log walls is mechanically less coupled to the pressure & thermal barrier of the studwall/joists, making the dynamic mechanical aspects of log houses less likely to compromise the air-tightness and thermal aspects of the envelope over time.

Some aesthetics to the log-look has been seen with the addition of 'Half logs, bolted in place on insulated wall systems.
5500 living sq ft ~` 11 btuh per sq ft at 5 below zero.
4-stage (7.4) Geothermal and Priority HW/ 100% recovery while/ and Cooling , beautiful Log-looking -Home
2nd 80-gal elct hw tank at 125
Some radiant in Kichen by under sink and MBed and bath. In basment flooring insulated 3/8 barrier and 1" foamboard 2003
OPEN WELL peak 13 gpm on highest 20-minutes recovery heating in HW, 11 in space heating (52deg)
bonus 3 bedsover 3-car gar FAMILY of 6-7

under 15,000 KWH annual fuel utilization, with LARGE mez Ret Air , to the surprise of HVAC'ers:
Any one can shoot for- this too, not a specialty:::
1.1/2deg diff at high side of the Mez, to anywhere, even standing at the bottom of the open stairwell to the basement in air-stabilization, -destratified as the blower on 600 cfm constantly filters also. Sealed return air system and supplies, 3 zones.

.... high 260 cooling and all electric bills last summer, this winter probably leaves all under 14,000 kwh, est.

D1 the Mini Splits would have save substantially on the second 2.0 GT in a zone, which as an addition had over a 15 year roi in this 9-year all time mess.
But even regularly as I read and discuss more now , hybrids or not, the customer will choose from among them more so...
T's

Shrinking 2# foam...I do not see it by my foam guy knows his business. It wouldn't matter if the 2x4 are off the wood and inch as you suggest. The logs are structural but by definition primitive. I would isolate the log with foam, it is outside the envelope for most of our intents and purposes. It will dry to the outside unaffected by the indoor atmosphere. The foam my shrink away from the logs without consequence since it will be "glued" to the studs. Foam is the long term solution with guaranteed return on investment, and hedge against high fuel prices.

Open sell is more flexible and a better sound attenuator and it "breathes" but these are attributes I seldom desire.

Slab-on-grade is a great value; air tight, easily insulated, vapor-proofed, sound proof and the perfect low temperature - low cost - heat emitter. I love a good slab! Good point on the ceiling. The whole point is to enjoy the rustic look, using natural locally available materials without compromise to comfort or economy.

We design and install radiant based systems every day and in my own recent remodel I foamed my 1921 farm house and installed a mini-split for cooling (it can heat too). Perfect comfort with farm house looks. No compromise.

Outdoor wood boilers keep the envelope tight and the fuel, soot, dirt outside. I have an electric boiler back-up for vacation and sloth.

Shrinking 2# foam...I do not see it by my foam guy knows his business. It wouldn't matter if the 2x4 are off the wood and inch as you suggest. The logs are structural but by definition primitive. I would isolate the log with foam, it is outside the envelope for most of our intents and purposes. It will dry to the outside unaffected by the indoor atmosphere. The foam my shrink away from the logs without consequence since it will be "glued" to the studs. Foam is the long term solution with guaranteed return on investment, and hedge against high fuel prices.

Open sell is more flexible and a better sound attenuator and it "breathes" but these are attributes I seldom desire.

Slab-on-grade is a great value; air tight, easily insulated, vapor-proofed, sound proof and the perfect low temperature - low cost - heat emitter. I love a good slab! Good point on the ceiling. The whole point is to enjoy the rustic look, using natural locally available materials without compromise to comfort or economy.

We design and install radiant based systems every day and in my own recent remodel I foamed my 1921 farm house and installed a mini-split for cooling (it can heat too). Perfect comfort with farm house looks. No compromise.

Outdoor wood boilers keep the envelope tight and the fuel, soot, dirt outside. I have an electric boiler back-up for vacation and sloth.

Shrinking 2# foam...I do not see it by my foam guy knows his business. It wouldn't matter if the 2x4 are off the wood and inch as you suggest. The logs are structural but by definition primitive. I would isolate the log with foam, it is outside the envelope for most of our intents and purposes. It will dry to the outside unaffected by the indoor atmosphere. The foam my shrink away from the logs without consequence since it will be "glued" to the studs. Foam is the long term solution with guaranteed return on investment, and hedge against high fuel prices.

Open sell is more flexible and a better sound attenuator and it "breathes" but these are attributes I seldom desire.

Slab-on-grade is a great value; air tight, easily insulated, vapor-proofed, sound proof and the perfect low temperature - low cost - heat emitter. I love a good slab! Good point on the ceiling. The whole point is to enjoy the rustic look, using natural locally available materials without compromise to comfort or economy.

We design and install radiant based systems every day and in my own recent remodel I foamed my 1921 farm house and installed a mini-split for cooling (it can heat too). Perfect comfort with farm house looks. No compromise.

Outdoor wood boilers keep the envelope tight and the fuel, soot, dirt outside. I have an electric boiler back-up for vacation and sloth.

Shrinking 2# foam...I do not see it by my foam guy knows his business. It wouldn't matter if the 2x4 are off the wood and inch as you suggest. The logs are structural but by definition primitive. I would isolate the log with foam, it is outside the envelope for most of our intents and purposes. It will dry to the outside unaffected by the indoor atmosphere. The foam my shrink away from the logs without consequence since it will be "glued" to the studs. Foam is the long term solution with guaranteed return on investment, and hedge against high fuel prices.

Open sell is more flexible and a better sound attenuator and it "breathes" but these are attributes I seldom desire.

Slab-on-grade is a great value; air tight, easily insulated, vapor-proofed, sound proof and the perfect low temperature - low cost - heat emitter. I love a good slab! Good point on the ceiling. The whole point is to enjoy the rustic look, using natural locally available materials without compromise to comfort or economy.

We design and install radiant based systems every day and in my own recent remodel I foamed my 1921 farm house and installed a mini-split for cooling (it can heat too). Perfect comfort with farm house looks. No compromise.

Outdoor wood boilers keep the envelope tight and the fuel, soot, dirt outside. I have an electric boiler back-up for vacation and sloth.

Cool Badg: !

OH-Here since a fam of 4-6 uses as much energy it seems ad a SUV 10,000 miles for Hot Waer Heating, and we KNOW we need a 100+ electric bill any ways ( one fam never gets below 330/ month of 7 people in large home (13,000 sq ft but budget near 730/mo e and 100-mo gas==  ALL radiant and 14 tons GT and nGas IBC Boiler 98+ rated)

2009 RADIANT but 5-ton in 2700 though I said 4 ton is too big... 3-ton would have fit, his first stage is 1,7 tons,,,
When I have budgets @ total 93to 97 /mo Harrisburg PA walkout basement insulated. un finished @ 32,000 just before the Bush Tax credits of 30%.
<< conventional Hi eff quotes were near 25000, he said.
2005 and 3400 over uninsulated basements    @ 144 to date

also knowing electric HW ~ 45-65/mo alone

some above are just not "paying for"  HVAC at all.

That other thread 5500 sq ft example well insulated @ 185/mo WHOLE HOME BILL is all I quote. (9-ton GEO 2003 under 40k no tax credit, all HW system, radiant in 60%, instant HW 3 zones and another 2.0 for above 3-car gar. 9-size-rated tons GT on open well
est savings over Hi-eff prop and Heat Pumps is over 2200 a year and he was quoted nearer eff as possible to GT: 24 to 30,00 conventionally Hi-Eff...

Do I hear an echo? :-)

It's less a shrinkage issue of the foam, but the seasonal shifting of the logs that's the problem with log homes, which is why I'd shy away from cc foam here.

The logs themselves DO offer a thermal break for the studwall, but the combination won't make code-min performance in his location with only 2" of cc foam between the studs, though it would if applied to the logs with the studwall fully inside the foam.

I'd be curious if your foam guy has experience with air-sealing & testing log homes, including follow-up blower door testing 3-5 years after installation. In my (admittedly limited) experience almost nothing keeps them air-tight as retrofits. (My brother's place is an ongoing air leak disaster, and seams sealed with foam have cracked & separated on the sunny side of the house where the seasonal dimensional dynamics seem higher.)

I would foam log to stud-at least 3.5". The logs will breath to the outside. They can fall off for all I care. Thermal envelope (and vapor barrier will be hanging from the studs). Of course they should be cured, but hey, you can't have it...for nothing. If he is using green logs open cell may work better, but how much will he have to use. With open-cell the vapor barrier will have to go on the inside of 2x4s and traditional build, but we haven't heard anything from Dan'l Boone for awhile. I think he wants to see the logs inside and out. Just talking to each other and the geo guy with the bad translating software...hheehehehehee

With deference to Dana's expertise on insulation the only opinion on code that counts is your building inspector's. If a log home is all you can afford, I'd tell your BI that fact and ask him how to get it done. If log houses are part of the culture in your part of the world, as they are here in Pa, the answer may as simple as pine and a minimum 8 inch diameter. The logs are a static R 12. Thermal mass enhancement gets you the rest of the way to R19. http://loghomescouncil.com/docs/EnergyPerformanceWP_2010.pdf
I'd find someone with experience. My brother's log cabin is still tight and comfortable five years later because the Amish men who helped him knew logs and log construction.

Kudos for your initiative. And spare a thought for the men who built the many log houses in my part of the world that are still standing 180 years later. Black locust throws sparks when you tackle it with a chain saw. These logs were hand hewn. Square.